1. Field of the Invention
The present invention relates generally to an apparatus and a method for extending a Universal Plug and Play (UPnP) network, and, more particularly, to a UPnP network area extension apparatus and method for extending an application range of a home network to an internet area.
2. Description of the Related Art
A home network generally includes a private network based on an Internet Protocol (IP). Such a home network connects various devices such as a Personal Computer (PC), a Smart Device, and a wireless device to a common network through middleware, which is a common virtual computing environment, in order to control the various devices.
Middleware enables communication between various devices by through peer-to-peer connection amongst the devices. Examples of proposed middleware include Home Audio/Visual Interoperability (HAVI), UPnP, Java Intelligent Network Infra-structure (JAVI), Home Wide Web (HWW), etc.
In a computing environment constructed through UPnP middleware among the above-listed examples of middleware, each device receives an allocation of an address from a server according to a Dynamic Host Configuration Protocol (DHCP), or an address selected through an auto IP designating function. Through the allocation of the address, devices communicate with each other, and search and inquiry are performed on a network.
A UPnP network technology is presently among the most frequently used home network technologies. The UPnP network defines a UPnP device, a UPnP service, and a protocol between the UPnP device and the UPnP service. Such a UPnP network includes a Controlled Device (CD), which is a home network device controlled while being connected to an IP based home network, and a Control Point (CP), which is a device controlling the controlled device. The control point is a device that performs a control for the controlled device. The control point requests an event from the controlled device, and receives the event from the controlled device. The controlled device is a device that performs a function determined according to a request of the control point. The controlled device transmits the requested event to the control point having requested the event when a state of the controlled device is changed.
Operation processes performed at respective steps during communication between UPnP network devices include an Advertisement process, a Discovery process, a Description process, a Control process, and an Event process.
In the Discovery process, the control point obtains link information indicating basic information and detailed information regarding devices located within the same network through a search message and an advertisement using a multicast protocol.
Meanwhile, a long polling technology among server push technologies corresponds to a technology in which, when a client transmits a HyperText Transfer Protocol (HTTP) request message, a server does not immediately respond to the message but piggybacks an event into a response message for the HTTP request message to transmit it when the event is generated. A Bayeux protocol using a concept of such a long polling technology can implement a publication/subscription system and perform one-to-one communication.
As described above, since the conventional UPnP network system is designed for the purpose of constructing a home network, the UPnP network cannot share information between two devices at random locations through an Internet connection.
Further, conventional UPnP networking may be cumbersome in that devices supporting a protocol such as DLNA (Digital Living Network Alliance) must access the same network or construct an ad-hoc network in order to share data.
In order to address the above-mentioned problems, there is a UPnP Remote Access (RA) technology that implements UPnP networking by connecting a device of an outside network to a home network by using a VPN (Virtual Private Network). However, the UPnP RA technology is limited to interworking between an outside device and a home network, and a home network manager must directly set up a management console within the home. Further, there is a disadvantage in that the UPnP RA technology cannot operate for a network using NAT (Network Address Translation).